Telephone-transmitter



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Patented June 4, 1889.

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UNITED STATES PATENT OFFICE.

' EDVIN S. DRAKE, OF CAMBRIDGE', MASSACHUSETTS.

-l TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 404,471, dated June 4, 18,89.

Application ned May 24, 1888.

To cLZZ whom imay concern,.-

Be it known that I, EDWIN S. DRAKE, 'of Cambridge, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Telephone-Tran sini-tters, which will, in connection with the accompanying drawings, be hereinafter fully described, and specifically defined in the appended claims. l

My invention relates to telephone-transmitters, so called, and has for its object the prevention of all counteractin g impulses which interfere with and modify the vocalized impulses while they are being directed to the diaphragm of the transmitter, and thereby to render more distinct and intelligible and facilitate telephonie communications;l and the invention consists in a transmitter possessing the novel features hereinafter fully set forth and claimed.

In the accompanying drawings, Figure l is an elevation of a transmitter front or door embodying my invention. Fig. 2 is a verticall section of the same, taken as on line X X, Fig. l, and showing my improved mouth-piece with its inlet and outlet air-conduits. Fig. 3 is a similar section of a Blake transmitter, (shown to enable me by comparison to more clearly illustrate and describe my invention.) Fig. 4 is a vertical section of a transmitter embodying the principle of myinvention in a modified form,

Although my invention is shown in the drawings as applied to the well-known Blake transmitter, it is equally well adapted to other forms of electric telephone-transmitters, and to those called mechanical telephones, wherein electricity is not employed as a transmitting agent. n l

My invention and improvements deal exclusively with that part of the construction of a transmitter which relates to conducting the sound-impulses to and from the outward face of the diaphragm, and not to the diaphragm itself and ts telephonie connections.

I construct in the door or front of the supporting case or box A of the transmitter, to or behind which the diaphragm is secured, a rectangular mouth-piece B, provided with an inlet-passage C and an outlet-passage D, arranged at right angles to each other and at an angle of forty-ive degrees to the face of the Serial No. 274,937. (No model.)

diaphragm E. The air-,conduit C receives the vocalized impulses imparted by the speaker and conducts them to the diaphragm E, and after having impinged the diaphragm such utilized and 'spent impulses are reiiected therefrom through outlet D in practical conformity to the natural law of reiiection of sound waves or vibrations from plane surfaces. Thus the successive impulses directed to the diaphragm are not counteracted, interfered with, or modiiied by the returning reflected impulse, and as a consequence greater purity of tone and distinctness of modulation in the corresponding vocalized impulses imparted at the opposite end of the telephonie line is obtained, and the commu nications thus conveyed are more clearly and intelligibly rendered, and the use of the telephone as a means of communication is thereby greatly facilitated.

The backward bevels m m on the front exterior edges of the projecting mouth-piece B, as well as the annular recess m around the circular mouth-piece or aperture B in the modification shown in Fig. 4, are for the purpose of deiiecting the overplus of impulses which do not enter the' mouth-piece or aper ture leading to the diaphragm, an d by so turning them aside preventing them from returning by reflection from the immediately-surrounding face or surface vof the tran smitter into the path of and confusing the impulses which proceed directly from the speaker to the diaphragm.

The modification shown in Fig. 4 places the inlet-passage of the mouth-piece in a'horizontal position and the outlet in a vertical position, while the diaphragm is set at an angle thereto, so that while the impulses directed toward the diaphragm are received obliquely through the horizontal passage C they are reiiected through the vertical passagey D, thus securing the same result as is obtained by the construction and arrangement shown in Fig. 2. Other forms of diaphragrns and other arrangements of independent inlet and outlet vpassages relatively thereto and acting on the same principle may readily suggest themselves to skillful constructers of such instruments for the same purpose and with the same results.

The advantages of myinvention above de= TOO scribed will be more readily understood and appreciated by reference to Fig. 3,which represents the old form of mouth-piece in its usual relation to the diaphragm. The vocalized impulses directed toward the diaphragm,

as illustrated by the broken lines, encounterY the sides n n of the mouth-piece B', and are in part reflected from side to side of the mouthpiece and across the path of the central impulses, which move directly toward the diaphragm, thereby disturbing and confusing the latter and impairing the purity of tone and modulations imparted by the corresponding vibrations at the opposite end of the telephonic line of communication; and this difficulty is still further increased bythe react-ion of the impulses so conducteddirectly against the diaphragm as they are reflected back in the opposite direction from Which they entered, and thus encounter and interrupt the successive inward Waves. The prevention of these difficulties in the manner and by means substantially as described constitutes the essential feature of my invention.

I claiml. A telephone-transmitter embodying the combination of a diaphragm E with a supporting case or front A, provided with separate but connecting inlet and outlet air conduits or passages, so respectively arranged relatively to the diaphragm that the vocalized impulses directed to the diaphragm through the inlet-passage will be reflected directly therefrom through the outlet-passage, as and for the purposes specified.

2. The combination of diaphragm E with a door or front A, provided with air-passages C and D, leading obliquely to and from the diaphragm at equal angles thereto, coinciding with the angles ot incidence and reflection of the sound-waves conducted thereto and therefrom through said passages, as specified.

EDVIN S. DRAKE.

W'itnesses:

HENRY WINN, EUGENE lIUMPI-nlzsv. 

